1,3,5-Benzenetricarboxylic acid (trimesic acid, TMA) was cocrystallized with 0.5 equiv. of 1,3,5-trihydroxybenzene (phloroglucinol, THB) to generate a close-packed non-interpenetrating planar mosaic motif. Both O-H···O and C-H···O hydrogen bonds were observed in the crystal lattice. Each THB molecule is hydrogen bonded to six adjacent TMA molecules to form a planar rosette-shaped structure, which constitutes the repeating units of a layer-type lattice.